The invention relates to a control system for electrically operated components of an automotive vehicle. Examples of such components are the horn, the lights, the fan for the heating and ventilation system, the air conditioning system, electrically powered windshield wipers, electric defroster, power windows, power door locks and power seats.
In a known control system, selector switches or buttons for various electrically operated components are mounted on the steering wheel. The selector switches or buttons for the components other than for the horn are connected with a signal transmitting unit which is likewise mounted on the steering wheel. The transmitting unit receives the signals which are generated by the selector switches or buttons upon activation of the same and transmits the signals to one or more receiving units mounted on a part of the vehicle other than the steering wheel. The receiving unit or units convert the signals sent by the transmitting unit into control signals which are forwarded to the operating elements serving to activate the electrical components. The transmitting unit and the receiving unit or units are connected with one another by a single conductor.
A control system of the type outlined above is disclosed in the West German Offenlegungsschrift 28 47 922. Here, the selector switches or buttons for the electrical components other than the horn are mounted on a pot-shaped cover of the steering wheel. Mounting of the selector switches or buttons on the steering wheel instead of the instrument panel, for example, makes it easier for the operator of the vehicle to observe and activate the selector switches or buttons. The control system of the Offenlegungsschrift also has the advantage that the signals for the different electrical components may be transmitted through a single conductor. This is made possible by the use of a transmitting unit which receives and transmits the signals from the various selector switches or buttons and the use of one or more receiving units which convert these signals into suitable control signals for the operating elements of the electrical components. The signals for the various electrical components are differentiated from one another by employing different pulses for the different electrical components. Since these selector switches or buttons are mounted on the rotatable steering wheel while the corresponding electrical components are mounted on another part of the vehicle, any conductor connecting the selector switches or buttons with the electrical components must be provided with a collector. The control system of the Offenlegungsschrift, in which only a single conductor for the electrical components other than the horn runs between the steering wheel and the body of the vehicle, thus provides considerable simplification as compared to a control system in which each electrical component is connected with the corresponding selector switch or button by an individual lead.
In the control system of the Offenlegungsschrift, a conventional arrangement is used for the horn. A switch or contact for the horn is mounted on the steering wheel while the horn itself, and possibly a relay for the horn, is or are mounted on the body of the vehicle. The switch for the horn is connected with the horn or its relay by a lead provided with a collector.
Although the control system of the Offenlegungsschrift has resulted in substantial simplification, further improvements are desirable.